National Hockey League rules

While the National Hockey League follows the general rules of ice hockey, it differs slightly from those used in international games organized by the International Ice Hockey Federation (IIHF) such as the Olympics. Infractions of the rules can lead to either the stoppage of play in the case of offside and icing calls, or a penalty call for more serious infractions.
During the 2004–05 lockout, the league changed some of the rules regarding being offside. First, the league removed the "offside pass" or "two-line pass" rule, which required a stoppage in play if a pass originating from inside a team's defending zone was completed on the offensive side of the center line, unless the puck crossed the line before the player.[73] Furthermore, the league reinstated the "tag-up offside" which allows an attacking player a chance to get back onside by returning to the neutral zone.[73] The changes to the offside rule were among several rule changes intended to increase overall scoring,[73] which had been in decline since the expansion years of the mid-nineties and the increased prevalence of the neutral zone trap.
Another rule difference between the NHL and the IIHF rules concerns how icings are called. In the NHL, a linesman stops play due to icing if a defending player (other than the goaltender) touches the puck before an attacking player is able to,[74] in con rast to the IIHF rules where play is stopped the moment the puck crosses the goal line. As a result of the rule changes following the 2004–05 lockout, when a team is guilty of icing the puck they are not allowed to make a line change, or skater substitution of any sort (except for a clearly injured player) before the following faceoff.[74]
The NHL and IIHF differ also in penalty rules. The NHL, in addition to the minor and double minor penalties called in IIHF games, calls major penalties which are more dangerous infractions of the rules, such as fighting, and have a duration of five minutes.[75] This is in contrast to the IIHF rule, in which players who fight are ejected from the game.[76] Usually a penalized team cannot replace a player that is penalized on the ice and is thus shorthanded for the duration of the penalty,[77] but if the penalties are coincidental, for example when two players fight, both teams remain at full strength. Also, unlike minor penalties, major penalties must be served to their full completion, regardless of number of goals scored during the power play.[77]
The NHL and the NHLPA created a stringent anti-doping policy in the new CBA of September 2005. The policy provides for a 20 game suspension for a first positive test, a 60 game suspension for a second positive test, and a lifetime suspension for a third positive test.[78]